Protein Polymer-Based Nanoparticles: Fabrication and Medical Applications

Abstract

Nanoparticles are particles that range in size from about 1⁻1000 nanometers in diameter, about one thousand times smaller than the average cell in a human body. Their small size, flexible fabrication, and high surface-area-to-volume ratio make them ideal systems for drug delivery. Nanoparticles can be made from a variety of materials including metals, polysaccharides, and proteins. Biological protein-based nanoparticles such as silk, keratin, collagen, elastin, corn zein, and soy protein-based nanoparticles are advantageous in having biodegradability, bioavailability, and relatively low cost. Many protein nanoparticles are easy to process and can be modified to achieve desired specifications such as size, morphology, and weight. Protein nanoparticles are used in a variety of settings and are replacing many materials that are not biocompatible and have a negative impact on the environment. Here we attempt to review the literature pertaining to protein-based nanoparticles with a focus on their application in drug delivery and biomedical fields. Additional detail on governing nanoparticle parameters, specific protein nanoparticle applications, and fabrication methods are also provided.

Keywords: bioimaging; biomaterials fabrication; drug delivery; nanomedicine; nanoparticles; protein.

Figure 1

Nanoparticle materials can be fabricated from a variety of protein sources, including silk, keratin, collagen, elastin, soy, and corn zein etc. These proteins can then be processed into particles with unique properties for biomedical applications.

Figure 2

A schematic of a nanoparticle spray-drying system in which the liquid polymer sample is sprayed alongside of heated gas in a chamber that leads to electrodes which are used to collect the charged sprayed nanoparticles. (Reproduced with permission from [102], Copyright Springer Nature, 2015).

Figure 3

This figure shows the basic mechanism used in high energy ball milling. As the cylinder rotates, the milling balls are accelerated and through physical force fracture the polymer material that is placed in the chamber.

Figure 4

(A) A model of protein nanosphere. The drug (red) is within a protein matrix (blue); (B) A model of protein nanocapsule. The drug is suspended and encapsulated by a thick protein polymer shell.